// 将其它数据转换为 string 值

// 将 String 当作普通函数使用时，
// 用于将其它数据转换为 string 值(原始类型)

let x = String();
console.log( x , typeof x );

x = String( null );
console.log( x , typeof x );

x = String( 0 );
console.log( x , typeof x );

x = String( '' );
console.log( x , typeof x );

x = String( false );
console.log( x , typeof x );

x = String( NaN );
console.log( x , typeof x );

x = String( undefined );
console.log( x , typeof x );

x = String( [ ] );
console.log( x , typeof x );

x = String( { } );
console.log( x , typeof x );